The Canadian eTA is a multiple-entry permit, which implies that Germans can visit Canada as many times as they need as long as the eTA is valid.
This may be especially useful for businesspeople who need to make frequent journeys to Canada, as the eTA is valid for both business and tourism purposes.
If the passport connected to the eTA becomes invalid, the visa waiver will no longer be applicable for future entries. In such circumstances, a new eTA must be applied for with the renewed passport.
No stay in Canada may exceed the maximum time limit, which is usually 180 days.