In short, NO.
However, there are several differences between the unregistered vs. registered NPL license types as follows:
UNREGISTERED (32 SLOTS)
If you are operating your server with the native, unregistered, "freebie" TeamSpeak 3 server license (32 slots max), then a Paypal "donate" button or hoster-imposed Google ads (for example) are allowed. Donations must be STRICTLY voluntary and cannot be enticed by any other "offers". For example, you may not entice donations by offering a special rank to a user, special server privileges, or "gifts" of any kind (whether tangible or non-tangible). We reserve the right to determine if your organization's activities are commercial in nature.
REGISTERED NPL (512 SLOT NON-PROFIT LICENSE)
If you are operating your server with a registered NPL (Non-Profit License, 512 slots max), then absolutely NO advertising or Paypal buttons of any kind are allowed anywhere on your site, your TeamSpeak 3 server, or anywhere else throughout your organization or your clan/guild activities, NO EXCEPTIONS. The purpose of this restriction is to avoid situations where an NPL hoster is in any way, shape, or form profiting or benefiting from their NPL license. As a reminder, the NPL license is STRICTLY for non-profit use. We reserve the right to determine if your organization's activities are commercial in nature.
If you require a Paypal button to help cover your clan or guild's operating expenses, you can either:
a) Use the TeamSpeak server's native UNREGISTERED, 32 slot license (not an NPL)
b) If you need more than 32 slots, consider purchasing an Annual Activation License (AAL). AAL licensees are allowed to have Paypal buttons, advertising, etc. Additional information and pricing for an AAL can be found here: http://sales.teamspeakusa.com/licensing.php
All situations with regard to piracy or abuse of non-profit based licensing are subject to our final interpretation and review.