This expression is a humorous way of saying that everything comes to an end
at some point.

The saying incorporates word play, since ein Ende can mean both “an
ending” and “one end,” allowing for the punchline that a sausage has two
ends rather than one. Originating from Francis Beaumont’s comedy
The Knight of the Burning Pestle, published in 1613, featuring Master
Humphrey, who courts a beautiful young girl named Luce. Humphrey tells
the young girl’s father that all things have an end – except for black
pudding, which has two. He expresses his endless love in this bloody
simile:
Although, as writers say, all things have end,
And that we call a pudding hath his two,
Oh, let it not seem strange, I pray, to you,
If in this bloody simile I put
My love, more endless than frail things or gut!
In Germany, this proverb was mentioned as early as 1867 in the German
dictionary of proverbs Deutsches Sprichwörter-Lexicon by Karl Friedrich
Wilhelm Wanderer. However, the mainstream use of this phrase can be
credited to German singer Stephan Remmler and his song Alles hat ein
Ende nur die Wurst hat zwei (1986).